Wednesday 22 August 2012 07.48 EDT
First published on Wednesday 22 August 2012 07.48 EDT

A map created by Amazon tracking the bestselling political books in the US state by state shows that conservative titles are outselling liberal books virtually everywhere – suggesting that if Americans' voting choices are linked to their book-buying habits, the Democrats are in for a tough ride this November.

Only six states are selling more liberal books bought than conservative titles: Vermont, Massachusetts, Rhode Island, Maryland, New York and DC. DC is the bluest of the blue states, with 78% of political purchases coming in blue, topped by Barack Obama's own two titles, Dreams From My Father and The Audacity of Hope.

One state, Pennsylvania, is exactly equally split between red and blue reading, with the rest of America – even the traditionally liberal California – opting for more conservative choices. The "reddest" state is currently Mississippi, where 72% of purchases are conservative titles, topped by Edward Klein's The Amateur, which argues that "Obama's toxic combination of incompetence and arrogance have run our nation and his presidency off the rails", and Bill O'Reilly's Killing Lincoln.

Obama can comfort himself, however, with the fact that his own title, The Audacity of Hope, is currently trouncing his rival Mitt Romney's No Apology: The Case for American Greatness, with 64% of Americans buying it compared with Romney's book. Vice president Joe Biden is doing less well: just 6% of readers have opted for his Promises to Keep, with 94% preferring Paul Ryan's Young Guns.

Amazon is making its political book classifications based on book promotional material and customer tags, and is calculating percentages daily for each state, based on shipping addresses for purchases. "Book sales by geography always have interesting things to say about our states, and an election season is a particularly good time to use this data to help customers follow the changing political conversation across the country," said Chris Schluep, senior editor for Amazon.com books. "But books aren't votes, so a map of book purchases may reflect curiosity as much as agreement."